1) National Institute of Genetics, Mishima, 411 Japan
2) Iwate Biotechnology Research Center, Kitakami, 024 Japan
Rice varieties grown in USA are traditionally classified into long, medium,
and short grain-types. The long-grain varieties have been considered as
indica, while the short and medium grained ones are japonica. The authors
collected 169 long-grain varieties from experimental stations in Louisiana,
Texas, Arkansas and other southern states, and examined them with regard to
phenol reaction, potassium chlorate (KC103) tolerance (1.5% solution,
immersed for 4 days), and isozyme alleles at seven loci (Table 1). Most of
the varieties (163/169) showed negative phenol reaction and high tolerance to
potssium chlorate, and their zymograms were those characterizing japonica.
Furthermore, 21 of them were examined with regard to the presence or absence
of a deletion at the ORF 100 region of Pst-12 fragment in chloroplast DNA
(cf. Kanno et al. 1993). This deletion is frequent in indicas but seldom
in japonicas (Chen et al. in press). All the cultivars examined were
non-deletion types which characterize japonicas.
Table 1. Alleles at seven isozyme loci detected in 169 American long-grain
cultivars
===============================================================================
Code Alleles observed at No. of alleles No. of
Amp-3 Acp-1 Cat-1 Est-2 Pgi-1 Pgi-2 Pox-2 differing from A cultivars
===============================================================================
A 1 2 2 0 2 1 0 Typical japonica 84
B 1 2 1 0 2 1 0 jaoponica-like
C 1 2 2 1 2 1 0 " 1 79
D 1 2 1 1 2 1 0 2 1
E 1 2 1 1 2 1 1 3 1
F 2 1 1 0 2 2 1 5 2
G 2 1 1 1 2 2 1 indica-like 6 2
Total 169
===============================================================================
References
Chen, W.B., Y.I. Sato, I. Nakamura and H. Nakai, 1993. Indica-japonica differentiation in traditional Chinese rice cultivars. Euphytica (in press).
Kanno, A., N. Watanabe, I. Nakamura and A. Hirai, 1993. Variations in chloroplast DNA from rice (Oryza sativa): differences between deletions mediated by short direct-repeat sequences within a single species. Theor. Appl. Genet. 86: 579-584.